As a method of acquiring an elevation value of a current position of a pedestrian or a vehicle, a method using a GPS signal or a method using a barometer is known. For example, Patent Literature 1 discloses a configuration including an atmospheric pressure measurement unit to measure an atmospheric pressure, a GPS reception unit to receive GPS data from a GPS, and an operation unit to calculate a road elevation and/or a road gradient, on the basis of the atmospheric pressure measured by the atmospheric pressure measurement unit and the GPS data received by the GPS reception unit, as a road gradient measurement system for obtaining the road elevation or the road gradient. Here, the GPS data includes elevation data and the operation unit operates a tentative elevation from the atmospheric pressure, corrects the tentative elevation with the elevation data, and calculates the road elevation.